Rounding of metallic-powder particles



Noml, 1927. 1,647,249

- E; PODSZUS ROUNDING OF METALLIC POWDER'QPARTIGLES' Filed July 16. 1926Patented Nov. 1, 1927; I 1,647,249 UNlTED STATES PATENT OFFICE.

EMIL PODSZUS, F BERLIN-FRIEDRICHSHAGEN, GERMANY, ASSIGNOR TO HARTSTOFF-METALL AKTIENGESELLSCHAFT (HAMETAG), OF BERLIN-COPENICK, GERMANY.

ROUNDING 0]? METALLIC-POWDER PARTICLES.

Application filed July 16, 1926, Serial No. 122,785, and in. GermanyDecember 22, 1924. I I

These moving members cause a positive pushing of the particles throughthe material in the casing, and compel-the powder For many uses to whichmetalic powder is particles to press and rub against each other, put, itis desirable to have the individual the amount of particles within theclosed particles of the powder, however, fine or casing being sufficientto prevent free passmall they may be, as round or spherical as sageduring movement; the particles thus possible. The present inventionrelates to exert pressure on .each other and become processes anddevices for converting powder rounded due to the mutual grinding action.particles that have sharp, jagged or tattered The novel process isparticularly effective edges into round particles. To this end the whena number of blades, screw propellers powder to be dealt with is placedin a closed or the like are provided which are curved or casing thatprevents the particles from evadmade to act in opposite directions sothat the ing the treatment which they are to undergo. powder particlesare ur ed from opposite The casing must be filled with powder todirections into the space etween the blades such an extent that itsparticles cannot evade and then against the walls of the casing. eachother in the rounding process to which The invention is illustrated inthe drawing they are to be subjected. This process conin' which l sistsin exerting a pressure on the particles Fig. 11s a diagrammatic verticalsection and causing them to rub against each other. of a device forcarrying out the afore- The rounding of the particles is broughtdescribed process and k about partly by altering their shape by ex- Fig.2 is an end view of a moving member ternal pressure and partly by therubbing off or propeller that sets the metallic powder in etc. of theprojecting edges of the same. motion. t

The process is brought about byforcing a The device consists of a casing1 to the quantity of the powder particles dealt with interior of whichaccess can be had through to move. As these particles are prevented anopening that is closed by a lid 2. Jourby the closed casing thatcontains them from nalled in the casing are two shafts 3 and 4 deviatinglaterally from their course, fric-- the inner ends of which carry powdermoving 30 tion must necessarily arise between the parmemberssuch asscrew propellers 11 and 12 ticles of the powder and their motion mustcash provided with a I plurality O blades also result in pressure beingexerted on the (three in the type illustrated) and a rearpowder. wardlybent arm 13 and 14 respectively that As a single rubbing and pressingoperareaches intotlie annular lateral recesses ofv tion ould t. b ffi it t ccompli h a the interior of the casing. The shafts 3 and completerounding of the particles and 4 have cogwheels 5 and 6 on their externalto deal with all the particles in the powends and the motion of a commonshaft 7 1s der, the process is arranged so that all transferred throughpin1o n 9 directly to the the particles of the powder circulate intheiogwheel 6 and through pinions 8 and 10 incasing and the saidoperation is repeated directly to the cogwheel 5 so that the shaftsagain and again. In these operations the 3 and 4 n their propellersrotate 111 PP powder -particles are continually remixed site directions.When the propellers or and after a few hours, or a longer period ifvanes 11 and 12 rotate the'1r screw motion the properties of the powderrequire it, all causes the masses of powder in their neighthe particleswill have the desired roundness oulhood to be pressed against each otherso or sphericality of shape. that they rub against each other and movePressure and motion is imparted to the back into the space at the rearof the propowder particles by twisted .vanes',blades pellers whence theyare again moved forscrew propellers or the like which are moved Ward sothat they travel cont nuously in a positively in the casing. To make theparcurved path or cycle substantially as indi'- ticles mix as intimatelyas possible and therecated by the arrow. The arms 13 and 14 by subjectall of them to the rounding treatssis the powder to act in this way,bement a plurality of the said movin memcause they have the form ofrearwardly bars are preferably employed and t ey are extending blades orshovels that seize the made different in shape, size and speed. powderin the lateral recesses of the eas- This invention relates to processand devices for the rounding of metallic powder particles.

ing and rotate it while urging it towards the middle space between thepropellers, so that the entire contents of the casing are forced toundergo the process by which the powder particles are rounded.

During this process the particles are pressed against each other,against the propeller blades and partly also against the walls of thecasing. At the same time the powder particles are caused to move withrespect to, each other and to rub against one another.

The quantity of powder put into the casablepart, of the propeller bladesare covered with powder. On account of the great resistance that theblades have to overcome and to obviate a whirling up of the powderparticles the speed of revolution should not e too rapid.

In the type of device illustrated the propellers are driven at difierentspeeds of revolution so that they keep on seizing different masses ofthe powder. The entire powder is kept continually in motion. Although aspecific form of propeller is shown the members for pressing and shiftinthe powder may be constructed in many other ways.

By this novel process it is possible to convert irregularly shaped metalpowder particles into approximately round bodies in a few hours and whenthe process is carried on for longer periods the space'occupied by toughingot-iron powder per unit of weight is reduced, due to the rounding ofits particles, to about 50% of the space taken up before application ofthe rounding process. In specific cases the exact figure will of cou:scdepend upon the size of the powder particles and .the nature of themetal of which they are composed.

Generally the metal powder treated in accordance with the novel rocesswill preferably be dealt. with in a ry condition, but small quantitiesof liquid, say a few per cent, may be added provided that the liquidused does not tend, to cause the articles to bind with each other or tomake t em plastic. By thus adding liquid the friction in the powder isreduced to a certain extent and the displacement of the powder particlesis thereby rendered easier. A liquid that might be used is oil, forexample, or organic liquids.

1. The method of rounding metallic pow.-

ing is such that thewhole, or a considerder particles which comprisessubjecting the mass of particles to a pressing and rubbingaction andpositively pushing said particles repeatedly through the mass whilebeing pressed and rubbed.

2. Apparatus for rounding metallic pow der particles comprising a casingfor holding the-particles, means within the casin for imparting motionto the particles and forcing them to rub and press against each other,and means in the casing for positively pushing said particles repeatedlythrough the mass while being pressed and rubbed.

3. Apparatus for rounding metallic powder particles comprisinga casingfor holding a mass of the particles, said casing hav ing lateralrecesses, means within the casing for subjecting said particles to arubbing and pressing action, and means for positively pushing theparticles in said recesses toward the zone of action of said firstmentioned means whereby to subject the particles to repeated rubbing andpressing.

4. Apparatus for rounding metallic powder particles comprising a casingfor holding a mass of particles, said casing having lateral recesses,rotative members within said casing for imparting motion to saidparticles and forcing them to rub and press against eachother, androtative arms extending into said recesses and operative to positivelypush the particles repeatedly through the mass.

5. Apparatus for rounding metallic powder particles comprising a, casingfor holding a mass of particles, rotative means in said casing forforcing said particles to rub and press against each other, and rotativemeans for positively pushing said particles repeatedly through the masswhile being pressed and rubbed.

6. Apparatus for rounding metallic powder particles comprising a casingfor holding a mass of the particles, said casing having lateralrecesses, rotative shafts extending into said casing, propellers rotatedby said shafts and operable to force the particles to rub and pressagainst each, other, and arms extendin into said recesses and rotated bysaid shai ts to positively push the particles in said recesses to mixthrough the mass.

In testimony whereof I have aflixed my signature.

EMIL PQDSZUS.

